Hipparcos Catalogue

A catalogue of 118,218 stars, mostly down to magnitude 8 but with a sampling
of dimmer ones (chosen for their unusual or interesting properties), surveyed
by the Hipparcos satellite and published in
1997. It contains the most precise measurements of positions, parallaxes,
proper motions, and magnitudes
ever made; although for stars dimmer than the ones surveyed, other catalogues
must still be used. The accurate parallaxes have led to a vastly improved
knowledge of the distances of stars out to a few hundred light-years from
the Sun. Magnitudes given by the Hipparcos dataset were measured using a
device sensitive to a wide range of wavelengths (mostly visual). These magnitudes
are unique to the detector on the satellite; they correspond roughly, but
not exactly, to visual magnitudes, and are called Hipparcos magnitudes.